Method and apparatus for the production of hollow bodies



March 28, 1950 w. WEBB ET AL 2,501,833

METHOD AND APPARATUS FOR THE PRODUCTION OF HOLLOW BODIES Filed Dec. 3, 1943 Patented Mar. 28, 1950 METHOD AND APPARATUS FOR THE PRO- DUCTION F HOLLOW BODIES Wesley L. Webb. Glenmoore, and Ray A. Randolph, Drexel Hill, Pa., and Robert J. Taylor, Claymont, Del., assignors to American Viscose Corporation, Wilmington, Del., a corporation of Delaware Application December 3, 1943, Serial N 0. 512,746

12 Claims. (01. 18-14) This invention relates to the production of artificial masses in the form of hollow globules of more or less ovoid or spherical shape, or a plurality of such globules arranged in a manner so that they resemble a string of beads.

It has heretofore been suggested to produce hollow bodies b continuously extruding a relatively thick filament or slender rod-like stream of a film-forming or filament-forming material and intermittently injecting a bubble of air or other gas to form a string of spaced hollow globules having the appearance of a string of beads. This process requires special equipment to assure proper control of the air-supply. It is difficult to obtain uniform results because intermittent flow of the air must be provided.

It is an object of this invention to avoid these diificulties by providing a process and arrangement whereby a continuous stream of air is utilized in the production of the hollow globules. A further object of the invention is to provide a process and arrangement whereby a tubular mass of the globule-forming material is continuously extruded and the gas therein is caused to expand the tubular mass along a portion of its length, after which the expanded portion may be sealed off from the rest of the tubular mass or severed entirely therefrom, such expansion and sealing or severing being repeated indefinitely. Further objects and advantages will b apparent from the drawing and its description hereinafter.

In the drawing, illustrative of the invention- 1 Figure 1 shows somewhat diagrammatically one arrangement, in elevation and partially in cross-section, of the invention;

Figure 2 is a detail view of the extrusion device of Figure 1;

Figure 3 is a plan view of the cutter device of Figure 1;

Figure 4 shows one form 'of product obtainable in accordance with this invention; and

Figure 5 shows another form of product obtainable in accordance with this invention.

Referring to Figure 1, an extrusion device 2 (which may be one of a plurality thereof) is arranged in the container 3 (which may take the form of a trough with its length extending at right angles to the plane of the drawing where a plurality of devices 2 are used). The device 2 is preferably arranged to extrudethe material 2 to be formed in a substantially vertical direction within the coagulating or setting bath in the container 3 and, as better shown in Figure 2, comprises in its simplest form a spinneret 4 having an orifice 5 through which a hollow needle 6 extends. munication with the orifice and surrounds the needle 6. The annular space 1 is connected to a supply of material to be formed b means of the passage 8 and the line 9. The needle 6 is connected to a supply of air or other gas under pressure by means of the passage l0 and line H.

The material to be formed may be provided in a supply vessel I2, an adjustable'measuring pump l3 and a filter l4 being disposed in the line 9 connecting the supply vessel I2 with the extrusion device 2. If desired, the upper region of the vessel l2 may be connected to a source of compressed air by line l5, and this line may be provided with a gage l6 and a pressure-regulating valve l'l.

Line ll may be provided with a gage I8 and an adjustable pressure regulator valve l9 to facilitate control of the gas or air flow therethrough.

A hollow tube of the material to be formed is formed by the extrusion device and extends upwardly therefrom in the form of a column. A cutting device 20 is arranged at a suitable distance above the device 2 and intermittently cuts the column of material.

The distance of the device 20 above the extrusion device 2 may vary widely. Preferably it is sufiiciently large so that the external surface of the formed material becomes coagulated and is substantially free of stickiness, though the material is still in a plastic condition. Under such conditions, no special treatment of the cutting or pressing portions of the cutter members is needed to prevent fouling thereof by adhesion of the material being cut, and yet the interior of the tube of material, not having had direct contact with the coagulating medium, is still sumciently adhesive to be effectively sealed by the pressing involved in the cutting action. When, however. cutting is eiTected at a position of the column where there is a tendency of the material to adhere to the cutter members, the operative portions of these members may be coated with an oil or grease or any other'sub- An annular space 1 is in com-.

stance which does not tend to adhere to the particular material being cut.

As one globule is cut from the column, the latter is sealed at its top and another globule begins to form immediately below the point of sealing as a. result of the fact that the lowest external liquid pressure exists along this portion of the column. The more or less spherical globules thus cut oil? rise to the surface of the coagulating bath from which they may be removed by any suitable device. For this purpose there is shown a pair of endless chains 2l driven continuously about the sprockets 22. The chains. carry a plurality of ropes 23 having curved prongs and are arranged to dump the globules onto a belt 24, which may run along one side of the trough 3 and convey the, globules to a drying device or to astation where they may be subjected to further treatment. preparatory to conveyance to a drying. device; or to other 4 stations for additional treatment.

A pump 25 may be arranged to circulate fresh coagulating medium at any desired rate into the vessel 3 through the pipe 26. An overflow pipe 21 directs the surplus medium into the reservoir bers. are rotated. Preferably, the speed of rotation is so adjusted as todmparta peripheralspeed at the peaks 30, substantially equal to, or. larger than the speed of. upward ascent of the tubular column extruded. The. members 29' are mounted for rotation onshafts 3li (which may extend the length of the vessel. 3,) which. carry driving gears 32- at one end thereof. Motion may be, imparted to one of. the shafts by a sprocket 33.01". equivalent means. One or both. f.'the, shafts may be supported in adjustable bearings 34. havingslotted bases. By adjusting the spacing between the opposed peaks or blades 30. of the, cutters, it is possible to sever the globules completely. or toseal the neck between, them by, pressing or pinching action, thereby forming a product like that shown in Figure 5. Another forrnof product of. dumbbell or peanut? shapemay be obtained by making alternate peaks. 3!] of thev cutter members higher than those between to effect alternate cutting and; sealing; between. adjacent globules; If desired, two or more sealingpeaks. may be disposed between the cutting peaks. Or, again, the cutter, members may be. constructed to. produce a mixture. of single globules, dumbbells, and/or three or four-celled strings. If desired, recesses of any shape may beformedin the periphery of a pair of discsor rolls which-may then.

amples of such materialsare solutions of: vinyl-- polyvinyl.

resins, such as polyvinyl alcohol, acetate, polyvinyl chloride, copolymers of vinyl chloride and vinyl acetateoracrylonitrile and such polymers and copolymers as have been after-chlorinated; also other resins such a polystyrene,

acrylic acid polymers, methyl and ethyl acrylate and methacrylate polymers, polyisobutylenes, polymers of chloroprene or butadienes or copolymers thereof with styrene or acrylonitrile; cellulose ethers and esters, such as cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate, ethyl cellulose, benzyl cellulose; also viscose, cuprammonium cellulose; caseins, soya-protein, zein, and gelatine.

These materials are extruded into a suitable coagulating bath of conventional. constitution, the particular bath depending upon the particular material to be coagulated. For example, a viscose solution may be coagulated in a dilute sulfuric acid bath containing a certain amount of sodium salts; A solution of cellulose acetate in acetone may be extruded into water containing a small swelling agent forthe cellulose acetate. A solution of a copolymer of vinyl acetate and Vinyl chloride in acetone may be extruded into a water bath in which the. acetone is not allowed to accumulate to acon'centration of over about 10 to Any gas. may be used, such as air, nitrogen.

carbon dioxide; hydrogen,- helium;. and the-like.

The gas-filled cell products of this invention may be used as a filling material for cushions, especially where elasticity and lightness of: weight are desired. Thus, they maybe used as flotation material in life preservers either, of the jacket, belt, or cushion type, and for this purposeit is preferable to employ such. products as aremadeof hydrophobic materials, especially of resins,

such as polyvinyl chloride. and the copolymers thereot. The products are useful as a heat in.- sulationfilling material, for which purpose they are especially adaptable? for filling the insulating.

walls of cold storagerooms or refrigerators.

It is to. be understood that changes and variationsmay bemade without departing from. the

spirit of the invention asdefined by the follow ing claims.

We claim:

1. Ina method of producing. hollow bodies, the.

steps of extruding a solution in a liquid of the materia-lto. be formed upwardly through an annular orifice into a coagulating. liquid medium to form a continuous tube, maintaining a COD?- tinuous column of gas. under pressure within the tube of material being extruded, and intermittently pressing the wall of thetube together while the material is still. plastic andtthe internal surface thereof is still in an adhesive conditionto seal said gas column, asthe material passes a predetermined. portion of its. path above the point of. extrusion, whereby the portions. of the material. immediately below the points of sealing are caused. to expand by the gas. pressure within.

2. In a method of producing hollow bodies, the steps of. extruding asol'uti'onin. a liquid of the material to be formed upwardly through an annular orifice into a coagulating, liquid medium. to form a continuous tube, maintainingga con'-- tinuous column of gas under pressure within the tube of material being extruded, and pressing the wall of the tube together while the material is still plastic and theinternal surface thereof is still in an adhesive condition to seal said gas column as the material passes a predetermined portion of its path above the point of extrusion within the medium, whereby the portion of the material immediately below the point of sealing is caused to expand by the gas pressure within.

3. In a method of producing hollow bodies, the steps of extruding a solution in a liquid of the material to be formed upwardly through an annular orifice into a coagulating liquid medium to form a continuous tube, maintaining a continuous column of gas under pressure within the tube of material being extruded, and cutting through the tube and simultaneously pressing the wall of the tub together while the material is still plastic and the internal surface thereof is still is an adhesive condition to seal said gas column as the material passes a predetermined portion of its path above the point of extrusion, whereby the portion of the material immediately below the point of cutting and sealing is caused to expand by the gas pressure within.

4. In a method of producing hollow bodies, the steps of extruding a solution in a liquid of the material to be formed upwardly through an annular orifice into a coagulating liquid medium to form a continuous tube, maintaining a continuous column of gas under pressure within the tube material being extruded, pressing the wall of the tube together while the material is still plastic and the internal surface thereof is still in an adhesive condition to seal said gas column as the material passes a predetermined portion of its path above the point of extrusion, whereby the portion of the material immediately below the point of sealing is caused to expand by the gas pressure within, and shaping at least some of the portions as they are expanded.

5. In a method of producing hollow bodies, the steps of extruding a solution in a liquid of the material to be formed upwardly through an annular orifice into a coagulating liquid medium to form a continuous tube, maintaining a continuous column of gas under pressure within the tube of material being extruded, pressing the wall of the tube together while the material is still plastic and the internal surface thereof is still in an adhesive condition to seal said gas column as the material passes a predetermined portion of its path above the point of extrusion, whereby the portion of the material immediately below the point of sealing is caused to expand by the gas pressure within, and cutting the material at selected points of sealing.

6. In a method of producing hollow bodies, the steps of extruding a solution in a liquid of the material to be formed vertically upwardly through an annular orifice into a coagulating liquid medium to form a continuous tube, maintaining a continuous column of gas under pressure within the tube of material being extruded, pressing the wall of the tube together while the material is still plastic and the internal surface thereof is still in an adhesive condition to seal said gas column as the material passes a predetermined portion of its path above the point of extrusion within the medium, whereby the portion of the material immediately below the point of sealing is caused to expand by the gas pressure within, and cutting the material at certain points of sealing.

7. Apparatus for producing hollow bodies com-z nel therein, means for continuouslymaintaining 5 a fluid under pressure' inthe channel as extrusion proceeds, a vessel containing a liquid bath for coagulating the-"material, said extruding means being arranged in the vessel to direct the material upwardly in the liquid, means for continuously maintaining a gas under pressure in the material as it is extruded, and means disposed in the vessel above the extrusion means for sealing the material at spaced points of its length.

8. Apparatus for. producing hollow bodi'escomprisingmeans for extruding I a'material as-a continuous article having a continuous hollow channel therein, means for continuously maintaining a fluid under pressure in the channel as extrusion proceeds, a vessel containing a liquid bath for coagulating the material, said extruding means being arranged in the vessel to direct the material upwardly in the liquid, and means disposed in the vessel above the extrusion means for cutting the material at spaced points of its length.

9. Apparatus for producing hollow bodies comprising means for extruding a material as a continuous article having a continuous hollow channel therein, means for continuously maintaining a fluid under pressure in the channel as extrusion proceeds, a vessel containing a liquid bath for coagulating the material, said extruding means being arranged in the vessel to direct the material upwardly in the liquid, means disposed above the extrusion means for sealing the material at spaced points of its length, means for cutting the material at selected points of sealing, and means for withdrawing the cut material from the vessel.

10. Apparatus for producing hollow bodies comprisin means for extruding a material as a continuous article having a continuous hollow channel therein, means for continuously main- F taining a fluid under pressure in the channel as extrusion proceeds, a vessel containing a liquid bath for coagulating the material, said extruding means being arranged in the vessel to direct the material upwardly in the liquid, means disposed above the extrusion means for sealing the material at spaced points of its length, and means for shaping the material between the points of sealing.

11. Apparatus for producing hollow bodies comprising means for extruding a material as a continuous article having a continuous hollow channel therein, means for continuously maintaining a fluid under pressure in the channel as extrusion proceeds, a vessel containing a liquid bath for coagulating the material, said extruding means being arranged in the vessel to direct the material upwardly in the liquid, and

means disposed above the extrusion means for both sealing and cutting the material at each of a plurality of spaced points of its length.

12. Apparatus for producing hollow bodies comprising means for extruding a material to be formed as a continuous article having a continuous hollow channel therein, means'for continuously maintaining a fluid under pressure in the channel as extrusion proceeds, a vessel containing a liquid bath for coagulating the material, said extruding means being arranged in the vessel to direct the material upwardly in the liquid, means disposed above the extrusion means his 7" 8 for-both sealingrand cutting-,the-materialiat each Number Name Date of. aplurality'offspaced points of; its, length, and. 1,394,270 Brandenberger. Oct. 18, 1921 I means for: shaping: the. material between the 1,990,434 Kohler-.. ,Feb. 5, 1935 points ofisealing'. 2,070,247 Weingandet a1. Feb. 9, 1937 I L. WEBB. 5 2,134,160 Korneggi Oct. 25, 1938 RA! A. RANDOLPH. 2,171,805; Picard Sept. 5, 1939 ROBERT J. TAYLOR. 2,187,432 Powers Jan. 16, 1940 2,199,425 Waring May 7, 1940 REFERENCES CITED 2,275,154 Merrill et a1. Mar. 3, 1942 The following references are of record in the 10 2277332 De Margetta 24, 1942 m i t s t 1,572 Scherer Oct. 12, 1943 2,332,671 Scherer Oct. 26, 1943 UNITED. STATES. PATENTS FOREIGN PATENTS Number Name Date 574,577 Royl'e: ,Jan. 5,1897 15 Number F Date 1,31 ,292. 3 Oct 7, 1 435.384 Great Brltam Sept. 9, 1985' 

